Alyssa Shepherd, 24, is accused of ignoring a bus stop arm, hitting four children with her vehicle. Three of those children—6-year-old twins Xzavier and Mason Ingle and their 9-year-old sister Alivia Stahl—were killed. A fourth child, 11-year-old Maverick Lowe, is recovering at a Fort Wayne hospital.

The crash happened on Oct. 30 near 4600 N. State Road 25 in the Rochester area. Indiana State Police said the bus driver put the stop arm down and the children were boarding the bus when a pickup truck hit them.

Shepherd told police she came around the corner, saw flashing lights and didn’t immediately realize it was a school bus. By the time she did, it was too late, she told investigators.

Police arrested Shepherd later that afternoon. She faces three counts of reckless homicide and a count of passing a stopped school bus resulting in injury.